1. Technical Field
The present invention relates to a method for manufacturing a physical quantity detector.
2. Related Art
Some acceleration detectors as physical quantity detectors are configured to utilize, for example, a phenomenon that the resonance frequency of a piezoelectric resonator element changes when a force in the direction of a detection axis acts on the piezoelectric resonator element, to detect acceleration applied to the acceleration detector based on this change in resonance frequency.
For example, JP-A-8-54411 discloses an accelerometer (acceleration detector) which has a double-ended tuning fork-type piezoelectric resonator element bonded to one of opposite angles of a frame-shaped parallelogram frame and is configured to apply a compressive force or tensile force to the other of the opposite angles, and a manufacturing method for the same.
The acceleration detector of JP-A-8-54411 includes a substantially flat plate-like center element including a fixed part and a moving part (vibrating mass) connected to the fixed part via a hinge and rotatable about the hinge, and a pair of substantially flat plate-like transducer elements which are welded to both sides of the center element and each of which has a double-ended tuning fork-type piezoelectric resonator element incorporated therein (see JP-A-8-54411, FIG. 3).
The acceleration detector is configured to detect acceleration from a difference in resonance frequency (frequency difference) changing in accordance with the acceleration applied, between the pair of double-ended tuning fork-type piezoelectric resonator elements.
According to the manufacturing method of JP-A-8-54411, in the acceleration detector, the center element is held on a wafer, during the manufacturing, via a separation tab provided on the outside of a placement ring situated on an outer perimeter. After the manufacturing, the separation tab becomes broken, thus separating the center element from the wafer.
However, according to the manufacturing method of JP-A-8-54411, a free end side of the moving part (vibrating mass) on the inside of the placement ring, of the center element, is rotatable (displaceable) about the hinge during the manufacturing.
Thus, according to the manufacturing method of JP-A-8-54411, the moving part and the hinge of the center element of the acceleration detector may become damaged by an external force applied, for example, when shaping by wet etching is carried out or when the pair of transducer elements is welded.